A common technique for forming concrete walls for buildings is to provide a mold made of a pair of spaced apart, parallel sheets between which the concrete is poured and cured. Then the sheets are removed, leaving the finished concrete wall.
Insulated, composite concrete walls have been produced by using foam plastic sheets as the mold forming sheets and leaving these in place after the concrete is cured to provide a composite concrete-plastic sheathed wall. This requires forming the plastic mold forming sheets of numerous smaller plastic panels that are secured together, edge to edge, to make up a sheet.
Various types of tie members have been used to interconnect the mold forming sheets and to hold them in their spaced apart positions during the concrete casting operation. In casting composite walls using plastic mold forming sheets which remain with the concrete, prior tie members have included a pair of plates interconnected by horizontally extending tie rods. These plates have been fastened within pockets or recesses formed in the plastic panels so that they also assist in aligning and securing adjacent panels together to form a single sheet. An example of this type of construction is illustrated in Canadian Pat. No. 1,187,671, issued May 28, 1985 to Hunter.
In the foregoing tie members the plates, which are made of plastic materials, and the means for fastening the tie rods and the plates together, are subject to being easily damaged by heat due to fires. Moreover, because of the substantial hydrostatic forces encountered during the pouring of concrete, there is a tendency for the foam plastic panels to move or "float". The prior tie members are generally inadequate to completely prevent this kind of movement.
Consequently, the invention herein relates to an improved tie member and wall construction wherein the plastic panels are immobilized against "floating" or movement due to the hydrostatic pressures encountered in pouring and curing the concrete. In addition, the improved tie member structure is better able to resist and to dissipate heat so as to provide a better fire resistant wall construction without reducing the insulation value of the composite wall construction.